125 A MCCB with 187 kA interrupting capacity at 240 V
The Siemens SENTRON 3VA1112-5EF32-0AC0 is a 3-pole molded case circuit breaker rated for 125 A continuous current and delivering 187 kA interrupting capacity at 240 V, 121 kA at 415 V, and 75.6 kA at 440 V. This interrupting performance means it can safely clear high-fault currents on the secondary side of a distribution transformer or at a large motor control center without cascading upstream — a key consideration when the available fault current at the panel exceeds what a standard 65 kA MCCB can handle. The TM240 thermal-magnetic release provides fixed magnetic pickup and adjustable long-time delay (tr max. 1 s), letting you coordinate with downstream feeders.
Thermal derating and panel integration
The 125 A rating holds flat from 40 °C to 50 °C, then derates to 120 A at 55 °C, 117.5 A at 60 °C, 115 A at 65 °C, and 112.5 A at 70 °C. In a sealed enclosure with multiple breakers ganged, that derating curve is what governs the real-world ampacity — not the nameplate 125 A. The 70 mm depth and 76.2 mm width fit a standard 3-pole MCCB footprint on a DIN rail or panel-mount base, with IP40 protection on the front face suitable for general-purpose indoor switchgear.